The compound 6-hydroxy-2-(4-hydroxyphenyl)-3-[4-(2-piperidinoethoxy)benzoyl]benzo[b]thi ophene, or raloxifene, is an important member of the class of compounds known as selective estrogen receptor modulators(SERMs). That compound is disclosed and claimed in U.S. Pat. No. 4,418,068.
Several methods of preparing benzo[b]thiophenes including raloxifene, have previously been disclosed (See, for example, U.S. Pat. Nos. 4,133,814, 4,358,593, 4,380,635, 5,523,416, 5,554,755, 5,606,075, and 5,606,076). In the event that the starting materials or the reagents necessary for the processes described in the aforementioned U.S. patents become scarce or unavailable, it would be advantageous to have alternative commercial processes for the preparation of benzo[b]thiophenes. The present invention provides both intermediates and synthetic routes for preparing the intermediates, and for preparing substituted benzo[b]thiophenes therefrom.